Distributing conveyor system for a rotary concrete mixing or other truck

ABSTRACT

A distributing conveyor system for a rotary concrete mixing truck adapted for installation on the truck frame and, when thus installed, embodies a single continuous conveyor unit which is capable of universal compound swinging movement in both vertical and horizontal planes, as well as being longitudinally shiftable to vary its effective length. The conveyor unit is at all times maintained in effective concrete-receiving register with the discharge hopper of the mixing truck and, by reason of its universal swinging and sliding movement, either uphill or downhill concrete distribution is made possible. By reason of its longitudinal shifting movement, either proximate or remote concrete placement may be effected.

United States Patent [191 Spellman, Jr.

1451 Feb.4, 1975 {75] Inventor: Francis T. Spellman, Jr., Blue Springs,Mo.

[73] Assignee: Symons Corporation, Des Plaines,

Ill.

22 Filed: rm. 1, 1972 21 Appl.No.:3l1,225

Related U.S. Application Data [62] Division of Ser. No. 208,682, Dec.16, I971.

[52] U.S. Cl. 214/8326, 198/126 [51} Int. Cl 1360]) 3/16 [58] Field ofSearch 214/8326, 520,521; 198/118, 126

[56] References Cited v UNITED STATES PATENTS 2,503,129 4/1950 Pautz214/8326 X 2,564,020 8/1951 Mengel 214/8326 5/1970 Benedict et al n214/8126 X 8/1972 Rossi 214/8326 X Primary ExaminerAlbert .I, MakayAttorney, Agent, or Firm-Norman H. Gerlach [57] ABSTRACT A distributingconveyor system for a rotary concrete mixing truck adapted forinstallation on the truck frame and, when thus installed, embodies asingle continuous conveyor unit which is capable of universal compoundswinging movement in both vertical and horizontal planes, as well asbeing longitudinally shiftable to vary its effective length. Theconveyor unit is at all times maintained in effective concrete-receivingregister with the discharge hopper of the mixing truck and, by reason ofits universal swinging and sliding movement, either uphill or downhillconcrete distribution is made possible. By reason of its longitudinalshifting movement, either proximate or remote concrete placement may beeffected.

8 Claims, 16 Drawing Figures PMENTEU SHEET 3 [IF 7 min PATENTED 41915SHEET 7 BF 7 mmm ms EWNQ DISTRIBUTING CONVEYOR SYSTEM FOR A ROTARYCONCRETE MIXING OR OTHER TRUCK This is a division of pending U.S. patentapplication Ser. No. 208,682, filed by me on Dec. 16, l97l and entitledDISTRIBUTING CONVEYOR SYSTEM FOR A ROTARY CONCRETE MIXING OR OTHERTRUCK."

The present invention relates generally to a vehiclemounted concretedistributing conveyor system which is designed for use primarily. butnot necessarily. in connection with a wide variety of concrete mixingtrucks of the ready-mix type and has particular reference to anarticulated conveyor structure or system embodying a single elongatedconcrete conveyor unit which is of the fixed length endless belt typeand, by reason of the numerous placement positions of which it iscapable of assuming, is capable of performing both long and shortpouring operations at varying pouring levels in amanner which isconsiderably more simple and efficient than is the case with any presentday vehicle-mounted concrete distributing conveyor system which utilizesa single extensible and contractible conveyor unit or two or moreserially arranged conveyor units which are disposed in end-to-end elbowjoint fash- IOI'I.

Heretofore, where a single conveyor unit is employed in connection witha vehicle-mounted concrete distribution system, it has invariably beenthe practice to provide a concrete-receiving hopper at the receiving orproximate end of the conveyor belt and to mount the conveyor unit as awhole for swinging movement about the vertical axis of such hopper. Thehopper remaining at all times in concrete-receiving register with thedischarge trough or funnel leading from the rotatable drum of theassociated ready-mix truck. Long and short pour operations are effectedby causing the conveyor unit to be extended or contracted, as the casemay be. Lateral pours are effected by swinging the conveyor unit fromside to side while various pouring elevations are accomplished byraising or lowering the discharge end of the conveyor unit, usually bymeans of an hydraulic lift cylinder. It is obvious that with aconcretedistributing system of this character, the shortest pour whichcan be accomplished is a direct function of the extent to which theconveyor unit can be shortened or contracted. It is also obvious thatshort down-pours in any direction are limited not only to minimumconeyor length but they frequently are limitedby the presence of nearbyobstructions such as buildings or partially completed buildingerections, trees, wall surfaces or the like. In the presence of suchobstructions, considerable maneuvering of the associated truck may benecessary in order to attain a given pour since it may be impossible tomaneuver the conveyor unit on the truck into pouring position unless thetruck is disposed in a conformable position. In some instances. the useof the conveyor unit alone is entirely precluded and it is necessary toemploy portable ground conveyors or resort to manual batch pouring.

To a certain extent. these limitations are also Present in connectionwith a vehicle-mounted concretedistributing system employing pluralconveyor units which are arranged in end-to-end fashion and have betweenthe adjacent or contiguous ends an elbow or hinge-type joint for thepurpose of permitting articulation of the units. To conduct whatordinarily amounts to a short pour operation, i.e.. a concrete placementin the vicinity of the associated truck, there must be resorted to along pour procedure involving a feed out of the concrete. coupled with areentrant feed back to the short pour location. In such instances. thepresence of nearby obstructions more frequently precludes such a pouringoperation than is the case where a single extensible and contractibleconveyor unit is employed.

Another limitation that is attendant upon the construction and operationof a present day concretedistributing system of either the single ormultiple conveyor unit type resides in the obstruction which the truckitself offers to freedom of conveyor unit movement so that closebackward pours. i.e.. forwardly of the rear wheels of the truck, cannotbe accomplished.

A further and serious limitation that is present in connection with anycurrent concrete distributing system of the vehicle-mounted type,whether embodying a single conveyor unit or multiple articulatedconveyor units, arises in connection with the problem of convenientlystoring the conveyor unit or units during transit or drive of theassociated truck to an from a given operating site or location.Disconnecting a given conveyor unit and rearranging its position on thetruck involves considerable labor, usually requiring the services of twoor more operators, and these difficulties are greatly magnified insub-zero temperatures where component parts of the conveyor system maybe frozen together.

Still another limitation that is present with a conventionalvehicle-mounted concrete-distributing system is concerned with thematter of conveyor leveling to pre' vent spilling of concrete over thesides of the endless conveyor belt during concrete pouring operations.On uneven terrain, ifthe rotary concrete mixing truck, i.e., ready-mixtruck, is not seated or positioned squarely on the ground so that whenthe single or multiple conveyor unit is extended, it assumes asubstantially horizontal position insofar as its transverse direction isconcerned. maximum pouring rate cannot be attained and it is necessaryto reduce the pouring rate to prevent lateral or sidewise concretespillage. The usual remedy is to level the truck by the use of jacks andthis. of course, is extremely time-consuming.

The present invention is designed to overcome the above-notedlimitations that are attendant upon the construction and use of anypresent day concrete distributing system for a ready-mix truck and.toward this end, the invention contemplates the provision of a systemwherein a single non-extensible and noncontractible conveyor unit isemployed, the unit being permanently mounted on the truck chassis insuch a manner that it is capable of a wide variety of movements so as toaccommodate both long and extremely short concrete pours and at variouselevations. To accomplish this. the conveyor unit is slidably mountedfor endwise movement in and through a carrier frame and from a fullyretracted position wherein the discharge or head end of the conveyorunit is in close proximity to the frame and a fully extended projectedposition wherein the tail end of the unit is in close proximity to theframe. The carrier frame is mounted for rotation about a vertical axisat the outer end of a horizontally elongated supporting bracket which isof appreciable length and, in addition, is hinged at its inner orproximal end to swing laterally back and forth about a substantiallyvertical axis. The length of this bracket is equal at least to one-halfthe over-all width of the truck so that in either extreme position ofthe bracket, the carrier frame for the conveyor unit lies outside thelateral confines of the truck. By such an arrangement. when thesupporting bracket is in either extreme lateral position, the carrierframe may be rotated so as to swing the fully or nearly fully projectedconveyor unit backwardly to accommodate concrete pours at regions whichare disposed forwardly of the rear wheels of the mixing truck. When thehinged supporting bracket is disposed in this overhanging relationshipwith respect to one side of the truck and the fully projected conveyoris swung backwardly to such an extent that it extends in thelongitudinal direction of the truck chassis, it may be brought intocontiguity with one side of the truck body and caused to come to rest ina stored or parked position on the adjacent rear wheel fender where itassumes an out-of-the-way position while the ready-mix truck is intransit from a concrete-receiving place to a place of use or vice versa.A further feature of the present invention resides in the provision of ameans whereby the hinged supporting bracket may be swung in the mannerof a pendulum and throughout a small angle in order to vary thetransverse inclination thereof for conveyor unit leveling purposes inthe event that the truck becomes supported on uneven terrain and therebycauses sidewise tilting of the conveyor unit.

The provision of a concretedistributing conveyor system which is, to alarge extent. hydraulically powered in that hydraulic power means areprovided for driving the endless belt of the conveyor unit, foreffecting endwise sliding movement ofthe conveyor unit with respect tocarrier frame in order to vary the length of the concrete pour. forraising and lowering the discharge end of the conveyor unit in order toaccommo date different pouring levels, and for leveling the conveyorunit in order to compensate for unevenness of the terrain over which theassociated truck is positioned; on in which a separate hydraulic pump isemployed to drive the conveyor belt of the conveyor unit so that thehydraulic operation of the other hydraulic components which areassociated with the system will not deprive the conveyor belt of itspower and constant belt speed throughout a variable range may beobtained; one which is capable of installation as original equipment ona rotary concrete-mixing truck or is capable of readily being installedon an existing ready-mix truck; one which is relatively simple in itsconstruction and. therefore, requires no degree of unusual skill for itsoperation and, hence, may be operated by the average truck operator; onewhich is comprised of a minimum number of parts, particularly movingparts, so that it is unlikely to get out of order; one which is ruggedand durable and will, therefore, withstand rough usage; one which iscapable of ease of assembly and dismantlement for purposes ofinspection, replacement or repair of the component parts thereof; onewhich is easy to clean in between pouring operations; and one which,otherwise, is well-adapted to perform the services required of it. arefurther desirable features which have been borne in mind in theproduction and development of the present invention.

Other objects of the invention and the various advantages andcharacteristics of the present concrete distributing conveying systemswill be apparent from a consideration of the following detaileddescription.

The invention consists in the several novel features which arehereinafter set forth and are more particularly defined by the claims atthe conclusion hereof.

In the accompanying seven sheets of drawings forming a part of thisspecification, two illustrative embodiments of the invention are shown.

In these drawings:

FIG. I is a top plan view of a concrete-distributing conveyor systemembodying the principles of the present invention and showing the sameoperatively installed upon a rotary concrete mixing truck;

FIG. 2 is a side elevational view of the particular structure of FIG. 1;

FIG. 3 is an enlarged vertical transverse sectional view taken on theline 3-3 of FIG. 2;

FIG. 4 is an enlarged vertical transverse sectional view taken on theline 4-4 of FIG. 2, the conveyor boom chain drive being omitted in theinterets of clar- FIG. 5 is a fragmentary enlarged plan view of aportion of the structure shown in FIG. I, the conveyor boom or unit andits carrier frame being shown in a different position;

FIG. 6 is a side elevational view of the structure shown in FIG. 5;

FIG. 7 is an enlarged top plan view of that portion of the structure ofFIG. 2 which is represented by the line 7-7;

FIG. 8 is a vertical longitudinal sectional view taken on the line 88 ofFIG. 7;

FIG. 9 is an enlarged side elevational view of that portion of thestructure of FIG. 1 which is represented by the line 9-9;

FIG. 10 is a plan view of the structure shown in FIG.

FIG. 11 is a plan view of the concrete-distributing conveyor system,largely schematic in its representation, showing the unitary conveyorunit or assembly in various distributing positions;

FIG. 12 is a rear end view of said concretedistributing conveyor system,showing the same operatively mounted on a rotary concrete-mixing truck,the disclosure being largely schematic and illustrating the conveyorunit or assembly in various distributing positions;

FIG. I3 is an hydraulic circuit diagram of the control mechanism whichis associated with the concrete distributing conveyor system;

FIG. I4 is a plan view similar to FIG. 10 but showing a modified form ofconveyor boom;

FIG. I5 is a side elevational view of the structure shown in FIG. 14;and

FIG. 16 is a fragmentary detail view of a portion of the structure shownin FIG. 15 with the boom-locking mechanism in its retracted position.

Referring now to the drawings in detail and in particular to FIGS. 1, 2,11, and 12, the concrete-distributing conveyor system of the presentinvention is adapted for use in connection with any one of a number ofconventional portable rotary concrete-mixing trucks of the type thatembodies an elongated chassis or frame structure to which the conveyorsystem may be secured. Such trucks are commonly known and referred to inthe industry as ready-mix trucks and, as a consequence, such designationwill be employed throughout this specification and in the appendedclaims at the conclusion hereof. In FIGS. I and 2 of the drawings.

there is illustrated a conventional ready-mix truck 10, and it has beenselected for environmental purposes in connection with the presentinvention and comprises a chassis or frame structure 12. The latter issupported on dirigible or steerable front wheels 14 and powerdriven rearwheels 16. An operator's cab 18 is mounted on the front end of the framestructure 12. The truck is provided with front and rear drum supports 20and 22 which project upwardly and forwardly from the frame structure 12and serve rotatably to support therebetween a forwardly and downwardlyinclined concrete-mixing drum 24. As is conventional and well known inthe art, the drum 24 is provided with internal mechanism (not shown) bymeans of which the concrete which is undergoing mixing within the drum24 during rotation of the latter is elevated and then discharged fromthe rear end of the drum and deposited into fixed discharge pan 26 atthe rear end of the frame structure 12 of the truck. From the pan 26,the mixed concrete in wet from flows downwards through a downchute 28and then into a movably mounted concrete placement chute 30 which,according to the present invention, is employed for feeding the concretein stream form to the distributing conveyor system constituting thepresent invention. A drum-loading hopper 32 above the discharge pan 26is provided for the purpose of introducing raw materials into the drum24 during charging of the latter. The arrangement of parts thus fardescribed is purely conventional in its design and no claim is madeherein to any novelty therein, the novelty of the present inventionconsisting rather in the association of the chute 30 with the concretedistributing conveyor system which is designated in its entirety by thereference numeral 50 and the nature of which will be more fullydescribed subsequently.

Still referring to FIGS. 1 and 2, the concretedistributing conveyorsystem 50 is in the form of an assembly of components including anelongated conveyor boom 52 of the endless belt type (see particularlyFIGS. 7 and 8). Such boom is slidable lengthwise in and through atiltable traverse carrier frame 54, the latter being mounted firfore-and-aft tilting movement on a turntable 56 which is capable ofrotational movement about a substantially vertical axis on the distal orouter end of a pivoted or hinged support bracket 58 (see H05. 5 and 6).The proximate or inner end of said support bracket 58 is pivotallyconnected to a pendulum bracket 60 which, in turn, is pivotallyconnected to a mounting fixture 62. The latter is fixedly mounted on theextreme rear end of the truck frame structure 12, preferably at a regionadjacent to the rear left-hand corner of the latter as viewed in FIG. 1.The pendulum bracket 60 is capable of limited swinging movements in avertical transverse plane for conveyor boom leveling purposes in amanner that will be made clear presently.

The aforementioned basic components of the present concrete-distributingconveyor system 50, namely, the conveyor boom 52, the traverse carrierframe 54, the turntable 56, the pivoted or hinged support bracket 58,and the pendulum bracket 60 are schematically portrayed in H05. 11 and12 without detailed disclosure thereof and in such a manner that thereare clearly shown the individual movements of which each component iscapable. The net result of all of these movements, in variouscombinations thereof, is to establish an infinite and universal movementof the conveyor boom 52 with respect to the truck frame structure l2 forconcrete placement purposes. in regard to these two views, namely, FIGS.11 and I2, only the outline of the conveyor boom 52 is illustrated invarious typical positions of the latter during concrete-pouringoperations, while the directional positions of the turntable bracket 58are illustrated by broken lines. It will be understood that all of thepositions of the conveyor boom 52 which are illustrated in FIGS. ll and12, are long pour positions, which is to say that the conveyor boomassumes a terminal position wherein the conveyor boom tail pulley whichis remote from the discharge end of the boom lies close to the traversecarrier frame 54 so that the concrete which is poured in the vicinity ofthe carrier frame 54 is conducted substantially throughout the entirelength of the conveyor boom before it is discharged from the boom overthe head pulley. The conveyor boom 52 is, however, capableof short-poweroperations wherein the conveyor boom 52 is slid endwise through thecarrier frame 54 to various positions in which the traverse frame isdisposed medially of the boom or to an extreme terminal position whereinthe head pulley lies close to said traverse carrier frame 54. The mannerin which these various illustrated or suggested positions of theconveyor boom may be attained will become more readily apparent when thenature of the invention is better understood.

As previously stated, the conveyor boom 52 of the concrete distributingconveyor system 50 is of the endless belt type and, as best shown inFIGS. 7 and 8, it is comprised of an elongated rectangular frameincluding a pair of sheet metal side plates (see also FIGS. 3 and 4). Tothe lower portions of the other sides of these plates are securedrespective channel members 72, the latter being substantiallycoextensive with the side plates 70 in the longitudinal directionthereof. Channel extensions 74 at the discharge end of the conveyor boom52 and in parallel and associated relation with the channel members 72are releasably and adjustably secured by pin and slot connections 76 tosaid channel members and constitute drive pulley mounting arms for aconveyor drive or head pulley 78. The pulley 78 is supported on themounting arms 74 by means of a pair of upstanding and spaced apartmounting plate 80. Similarly, at the receiving end of the conveyor boom52, channel extensions 82 are secured by pin and slot connections 84 tothe channel members 72 and constitute tail pulley mounting means for aconveyor tail pulley 86, the latter being rotatably supported on thechannel extensions 82 by a pair of upstanding and spaced apart mountingplates 88.

An endless flexible conveyor belt 90 passes around the drive or headpulley 78 and the tail pulley 86 and has its upper reach tractionallysupported on a longitudinal series of multiple troughing rollers, eachgroup of troughing rollers including a pair of upwardly and out wardlyextending inclined rollers 92 (see FIGS. 3 and 4) and a horizontalbottom roller 94 between but laterally offset with respect to theinclined rollers. The various groups of troughing rollers are suitablysupported by compound bracket assemblies 96 from respective transverseframe members in the form of horizontal angle pieces 98 (see FIG. 8)which extend between the side plates 70. Gusset plates 99 which areconnected to and extend upwards from the ends of the angle pieces 98serve to strengthen and reinforce the sheet metal side plates 70. Thelower reach of the conveyor belt is tractionally supported by aplurality of longitudinally spaced, transversely extending returnrollers 100 which are rotatably supported by suspension brackets 102.The latter are suitably fixedly connected to the inner faces of the sideplates 70.

The channel extensions 74 and 82 constitute means whereby conveyor belttension may be regulated. in order to facilitate such tensioning of theendless belt 90, belt take-up assemblies 104 (see FIG. 8) are fastenedto the channel members 72 and include thrust screws 106 which hear attheir ends against the inner ends of the channel extensions 74 and 82.By releasing the pin and slot connections 76 and 84 and properlymanipulating the take-up assemblies 104, proper belt tension may beattained, after which the pin and slot connections may again betightened.

A discharge hood 110 (see FIGS. 7 and 8) is operatively mounted on thechannel extensions 74 and projects below the level of the conveyor boomas shown in FIG. 8 of the drawings. An hydraulic drive motor M1 (seeFIG. 7) for the head pulley 68 is secured by a mounting bracket 112 toone of the channel extensions 74.

The conveyor boom 52 of the concrete-distributing conveyor systemembodies numerous incidental arrangements of a minor nature such asgusset plates, reinforcing struts, lateral side flanges, bolting meansand the like, such arrangements appearing in the drawings but being notdescribed herein since they do not constitute essential or importantfeatures of the invention. Still other illustrated details such aspiping and flexible conduit lines which relate to the hydraulic controlsystem for the concrete-distributing conveyor system 50 will bedescribed subsequently when the hydraulic system and its operation areset forth in greater detail hereinafter.

Considering now the traverse carrier frame 54 which supports theconveyor boom 52 and through which the boom is longitudinally slidable,the details of such traverse carrier frame are best illustrated in FIGS.3, 4, 5, and 6. It will be recalled that this carrier frame 54 iscarried at the outer or distal end of the pivoted or hinged supportbracket 58 which supports the turntable 56. The traverse carrier frame54 involves in its general organization a composite cradle-likestructure of inverted U-shaped design and including two vertical sheetmetal side plates 120 which straddle and are disposed slightly outwardsof the side plates 70 and the channel members 72 of the conveyor boom52, arch inwardly over the conveyor boom 52 as indicated at 122 in F105.and 6, and serve to supporttherebetween an upwardly opening rectangularconcretereceiving hopper 124. Upstanding elastomeric funnel sheets 126are secured in position on the upper rim of the hopper by means offastening strips 128. The sheet metal side plates 120 of the carrierframe 54 supported by means of a tiltable frame structure of cage-likedesign and including short vertical corner legs 130 at one end of saidframe structure and long vertical corner legs 132 at the other end (seeFIGS. 3, 4, 5, and 6). These legs have their upper ends secured tolongitudinally extending tubular side members 134. Upwardly and inwardlyinclined structural members 136 and 138 are secured to the lower ends ofthe corner legs 130 and 132, respectively, and also to medial regions ofthe tubular side members 134 and serve to render the tiltable framestructure rigid. As best illustrated in FIGS. 3, 6, and 8 of thedrawings, the lower ends of the long vertical legs 132 are connectedtogether by means of a crossbar 140 which underlies the conveyor boom52. The medial region of said crossbar has pivotally attached theretothe outer end ofa pluger 142, the latter being associated with anhydraulic lift cylinder 144 which is pivotally attached to the turntable56 and the nature and function of which will be made clear presently. Asset forth hereafter, the cylinder 144 is operable under the control of alift valve V4 (see F105. 1 and 13).

As previously stated, the conveyor boom 52 of the system 50 is slidablebodily and lengthwise through the traverse carrier frame 54 and,accordingly, the boom is guided in its lengthwise sliding movements bymeans of a longitudinal series of upper rollers and a similar series oflower rollers 152. The upper rollers 150 are rotatably mounted on theupper end portions of the corner legs 130 and 132 and are in the form ofholddown rollers which overlie the upper side flanges of the channelmembers 72 on opposite sides of the conveyor boom 52. The lower rollers152 are rotatably mounted on the lower end portions of the corner legs130 and 132 and underlie the lower side flanges of the channel members72 as best seen in FIG. 6. The conveyor boom 52 is held in alignmentwith the traverse carrier frame 54 by means of horizontal rollers 153which bridge the side flanges of the channel members 72 and also byhorizontal rollers 155 which bear against the lower side flanges of thechannel members 72. The rollers 152 are mounted on angle brackets whichare connected to the lower end portions of the long corner legs 132 andthe rollers 153 are mounted on angle brackets which are connected to thelower end portions of the short corner legs 130. From the abovedescription, it will be appreciated that the various rollers 150, 152,153 and 155 constitute confining guide rollers by means of which theconveyor boom 52 of the system 50 is constrained to move lengthwisethrough the traverse carrier frame 54 from substantially one end of theboom to the other and in either direction. The carrier frame 54 thusconstitutes the sole supporting means for the conveyor boom 52 in allpositions of the latter. It is to be understood that in all positions ofwhich the conveyor boom 52 is capable of assuming, the hopper 124 ismaintained in vertical register with the upper reach of the conveyorbelt 90 and also that, by reason of the various troughing rollers 92 and94 which are associated with the conveyor belt, the upper reach of thebelt will assume the trough-like condition in which it is illustrated inFIGS. 3 and 4 of the drawings. The drive motor M1 is a unidirectionalmotor and, therefore, the upper reach of the conveyor belt 90 iscontinuously driven in the direction indicated by the arrows in F165. 1,5, and 7. When the conveyor boom 52 is projected through the traversecarrier frame 54 to a position such as is shown in FIGS. 1 and 2 whereinthe discharge end thereof is remote from the carrier frame, a maximumlength long pour condition obtains. When the conveyor boom 52 isprojected in the opposite direction, i.e., so that the discharge end ofthe conveyor boom lies close to the traverse carrier frame 54, a minimumlength short pour condition obtains.

As previously stated, the traverse carrier frame 54 is tiltable bodily,together with the conveyor boom which is carried thereby, for rockingmovements about a horizontal axis in a fore-and-aft direction.Accordingly, and as previously stated, the traverse carrier frame 54 ismounted for tilting or rocking movement on the turntable 56 by means ofan upright U-stand 160 (see FIGS. 4, 5, and 6) which comprises a pair ofvertically extending spaced apart side arms 162 and a connectinghorizontal base member 164. The U-stand 160 is welded or otherwisefixedly secured to the turntable 56 and, thus, the U-stand may beregarded as constituting an element of the turntable assembly. Thevertical side arms 162 of the U-stand straddle the traverse carrierframe 54 and the upper regions of these arms are provided with inwardlyextending trunnions 166 which pass through holes in the tubular sidemembers 134 of the carrier frame 54 and constitute pivotal connectionsfor the frame and the conveyor boom 52 which is slidably supportedthereby. The central portion of the base member 164 of the U-stand 160is attached in diametric relationship to the upper surface of a circularhorizontally extending cogwheel 170 (see FIGS. 9 and which constitutesan element or part of the turntable 56. The latter further includes apivot shaft 172 which depends from the central portion of the cogwheel170 and is rotatably mounted within a vertically extending sleeve 174,the latter being carried at the extreme outer or distal end of thehinged support bracket 58 for the turntable 56. The lower end of thepivot shaft 172 projects below the sleeve 174 as shown in FIG. 6 andcarries a split clamping collar 175 to which the closed end of the liftcylinder 144 is pivoted. The lower end region of the sleeve 174constitutes a reaction point for the aforementioned lift cylinder 144.

The pivoted or hinged support bracket 58 for the turntable 56 is in theform of a generally trapezoidal frame structure of which the turntablesleeve 174 constitutes the outer or distal end piece thereof. The upperend of the sleeve is formed with a circular turntable bearing plate 175(see FIG. 4) on which the cogwheel 170 rests. The support bracketfurther includes an inner or proximate end piece 176 which also is inthe form of a vertically extending sleeve and is rotatably carried on agenerally vertically extending fixed supporting shaft 178. Thissupporting shaft 178 constitutes the main reaction member for the entireconcretedistributing conveyor system 50, the shaft being capable oflimited tilting movement in a plane which extends vertically andtransversely with respect to the truck frame structure 12, theaforementioned limited tilting movement being for conveyor-levelingpurposes as will be described presently. Accordingly, the supportingshaft 178 is fixedly secured at its upper and lower ends in a pair oflaterally extending ears comprising an upper ear 180 in the form of acog sector and, in addition, a lower car 182, both ears being secured toand forming a part of the aforementioned pendulum bracket 60. As shownin FIG. 6, the upper portion of the pendulum bracket 60 is pivotallyconnected as indicated at 184 for limited swinging movement on theaforementioned mounting fixture 62 on the rear end of the truck framestructure 12 throughout a small angle under the control of an hydraulicdevice in the form of a plunger 186 the outer end of which is pivoted tothe lower end of the pendulum bracket 60, and a cylinder 188 the closedend of which is pivoted to an appropriate point on the mounting fixture62. The cylinder 188 is operable under the control of a leveling valveV3 in a manner that will be made clear when the operation of theconcrete-distributing conveyor system 50 is set forth. Upper and lowerframe bars 192 and 194 which extend between the end portions of thesleeves 174 and 176, and diagonal struts 196 complete the pivoted orhinged support bracket 58 for the turntable 56.

As clearly shown in FIG. 10 of the drawings, the cogwheel at the outerend of the hinged turntable support bracket 58 is provided with anannular series of peripheral teeth 200 which cooperate with an arcuateseries of pinion teeth 202 on a dog 204. the latter being slidablelongitudinally on the upper frame bar 192 of the hinged or pivotedturntable support bracket 58. The dog 204 is movable between an advancedlocking position wherein its teeth 204 are in mesh with the teeth 200 ofthe cogwheel 170, and a retracted position wherein the cogwheel 170 isreleased by the dog 204 so that it may be rotated in either directionabout the substantially vertical axis of the pivot shaft 172, thuscausing the turntable 56 as a whole to rotate and effect directionaladjustment of the traverse carrier frame 54 and its associated conveyorboom 52. Such sliding movement of the dog 194 is effected under thecontrol of an over-center toggle device 206 including a looplike drawlink 208 and a manipulating lever 210 therefor, such lever being pivotedon an upstanding bracket 212 the lower end portion of which is fixedlymounted on the upper frame bar 192 of the support bracket 58 near theproximate end of the latter. Said dog 214 is provided with an arcuateseries of teeth 216 which are designed for cooperation or meshingrelation with an arcuate series of teeth 218 on the cog sector whichforms or constitutes the upper ear 180. The dog 214 is operable underthe control of an over-center toggle device 220 which is substantiallythe same as the toggle device 206. The toggle device 220 differs fromthe tggle device 206 only in that the slidably mounted dog 214 which isassociated therewith is biased toward its advanced locking position byway of a helical compression spring 222.

In addition to the parts or elements heretofore de scribed, theconcrete-distributing conveyor system 50 comprises an hydraulicallypowered chain drive mechanism by means of which the conveyor boom 52 maybe shifted lengthwise through the traverse carrier frame 54 in order tovary the length of concrete pour. Referring particularly to FIGS. 3,6,and 8, lengthwise conveyor boom movements are effected under thecontrol of a single length of chain 230. One end of the chain is securedto the medial region of a crossbar 232 which extends transversely acrossthe conveyor boom 52 and is secured to the underneath sides of thechannel members 72 in the vicinity of the tail pulley 76, while theother end of the chain is similarly secured to the medial region of acrossbar 234 which is secured to the underneath sides of the channelmembers 72 in the vicinity of the drive or head pulley 78. The chain 230projects longitudinally through the traverse carrier frame 54 and withinthe frame it makes a U-shaped or serpentine dip as indicated at 236 inFIGS. 6 and 8. The upper portions of the dip extend over a pair ofspaced apart sprockets 238, and the lower portion of the dip extendsunder and around a drive sprocket 240 which is fixedly mounted on thedrive shaft 242 of a reversible hydraulic boom motor M2. The boom motorM2 is operable under the control of a reversible boom extension valve V2in a manner that will be made clear when the hydraulic operation of theconveyor system 50 is set forth hereafter. As best shown in FIG. 3, thetwo sprockets 238 are carried at the upper end of an upstanding anglebracket 244 which is supported on and fixedly connected to a suspensionbeam 246, the latter being attached to the underneath side of thecrossbar I40 of the traverse carrier frame 54. The motor M2 is supportedfrom the suspension beam 246 by means of a motor mount 248.

From the above description, and with reference to FIG. 8 of thedrawings, it will be apparent that when the drive sprocket 240 isrotated by the boom motor M2 in a clockwise direction, the chain 230will be shifted lengthwise to the left as seen in this view, thusplacing that portion of the chain which extends between the crossbar 234and the drive sprocket 240 under tension so as to draw the conveyor boom52 to the left and thereby progressively shorten the effectiveconcreteconveying surface of the endless conveyor belt 90. Conversely,when the drive sprocket 240 is rotated in a counterclockwise direction.the chain will be similarly shifted lengthwise to the right so as todraw the conveyor boom in a direction which will lengthen the effectiveconcrete-conveying surface of the belt 90.

OPERATION OF THE CONCRETE DISTRIBUTING CONVEYOR SYSTEM A description ofthe operation of the herein disclosed concrete-distributing conveyorsystem 50 will be facilitated by reference to FIG. 13 which is anhydraulic circuit diagram illustrating schematically the dual pumpingsystem which is employed for actuating the various hydraulic powercomponents of the conveyor system 50. In this view, the fluid linesleading to such components are fully disclosed, whereas in the precedingviews, namely, FIGS. 1 to 12, inclusive, only fragmentary portions ofsuch fluid lines are disclosed.

According to the present invention it is contemplated that. in order tomaintain constant conveyor belt speed at all times, there shall be noreduction of the full line pressure which is maintained in the fluidlines leading to the belt drive motor MI. Accordingly, the hydrauliccircuit for the motor MI extends from an oil sump S. through a pump P],a conduit section II, a manual shut-off valve VI, a conduit section 13,the hydraulic motor MI, and conduit sections I5, 17, and 19 back to thesump S. By reason of the fact that the hydraulic motor M1 is flxed toand movable bodily with the conveyor boom 52 as previously described, itis necessary that at least certain portions of the conduit sections 13and 15 be flexible. Thus, in FIGS. 7 and 8, and elsewhere in thedrawings, the portions of the conduit sections 13 and 15 which aredesignated 13: and 15! are in the form of lengths of flexible tubing,while the portions which are designated 13p and 15p are in the form oflengths of rigid piping. It will be noted that the lengths 13p and 15pof rigid piping travel bodily with the conveyor boom 52 and connectthrough short reverse connections I3r and l5r with the lengths I31 and152 of flexible tubing. In order to prevent snarling of the flexibletubing lengths l3! and I5t, helical spring sheaths 250 are fixed to abracket 251 on the conveyor boom 52, surround portions of the lengths offlexible tubing and initiate or effect formation of flexible reversebends 13b and 15b. The latter vary or change in size as the conveyorboom moves through the carrier frame 54. The sheathes thus prevent theformation of kinks in the flexible tubing lengths. The aforementionedrollers 153 which guide the channel members 72 of the conveyor boom 52serve the additional function of guiding the reverse bends 13b and I5!)of the lengths I3! and 15: of the flexible tubing between the flanges ofthe channel members 72. Additional rollers 157 assist the rollers 153 inthus guiding said flexible tubing lengths.

Referring again to FIG. 13, lengthwise sliding movement of the conveyorboom 52 in opposite directions is effected under the control of areversing valve V2 which is associated with a second hydraulic pump P2.The latter pump serves to supply fluid (oil) under pressure to all ofthe hydraulic components of the concrete distributing conveyor system 50other than the belt drive motor MI, the valve V2 serving the boom motorM2, a valve V3 serving the leveling cylinder I88, and a valve V4 servingthe lift cylinder 144. For the convenience of the operator, the valvesVI, V2, V3, and V4 are mounted on a valve control panel 252 (see FIG. 2)which is suitably connected to one of the rear wheel fenders of theready-mix truck I0, preferably the rear left fender 254. By reason ofthis, said valves are readily accessible to the operator when theconveyor system 50 is to be used.

Upon manipulation of the valve V2 for boom extension purposes, i.e., toslide the boom lengthwise through the traverse carrier frame 54 to theright as viewed in FIGS. 2, 7, and 13, an hydraulic circuit will beestablished and will extend from the sump 5, through the pump P2, a pairof conduit sections 21 and 23, the reversing valve V2, a conduit section25, the motor M2, a conduit section 26, the valve V2, a conduit section29, and the conduit sections 17, 19 back to the sump S. The existence ofthis hydraulic circuit will cause the drive sprocket 240 to rotate in acounterclockwise direction as viewed in FIG. 13, thus placing thesection of the chain which extends between the sprocket 240 and thecrossbar 232 under tension so as to pull or shift the conveyor boom 52to the right and thus extend the boom and increase the length of theconcrete pour as previously described. If it is desired to shorten thelength of the concrete pour, the valve V2 is reversed so as to establishan hydraulic circuit which extends from the sump S, through the pump P2,the conduit sections 21, 23, the valve V2, the conduit section 27, themotor M2, the conduit section 25, the reversing valve V2, and conduitsections 29, l7, 19 back to the sump S. The existence of this latterhydraulic circuit will cause the drive sprocket 240 of the motor M2 torotate in a clockwise direction, thus placing the span or portion ofchain which extends between the drive sprocket 240 and the crossbar 234under tension so as to draw the conveyor boom to the left and thusshorten the length of the concrete pour.

If, at any time during concrete-pouring operations, the truck framestructure 12 should happen to rest on uneven terrain so that theconveyor boom 52 is tilted sidewise and, thus, is not level insofar asits transverse direction is concerned, this condition may be remedied bymanipulation of the leveling valve V3. Such valve is a reversing valveand manipulation thereof in one direction will establish an hydrauliccircuit which extends from the sump S, through the pump P2, the conduitsection 21, a conduit section 3I, the valve V3, a conduit section 33,the leveling cylinder 188, a conduit section 35, the valve V3, a conduitsection 37, and the conduit section I9 back to the sump S. Introductionof fluid under pressure into the cylinder I88 from the conduit section33 will serve to project the plunger I86 of said cylinder (see FIG. 6),thus causing the pendulum bracket 60 to swing throughout a limiteddegree to thus bring the conveyor boom 52 to a level condition insofaras its transverse direction is concerned, all in a manner that haspreviously been set forth. In order to swing the pendulum bracket 60 inthe opposite direction, the valve V3 is manipulated so as to establishan hydraulic circuit which extends from the sump S, through the pump P2,the conduit sections 21, 31, the valve V3, the conduit section 35, theleveling cylinder 188, the conduit section 33, the valve V3, and theconduit sections 37, 19 back to the sump 5.

When it is desired to raise or lower the boom, i.e., change itsinclination by raising or lowering the dis charge end thereof, the liftvalve V4 is manipulated. In order to raise the discharge end of theboom, the valve V4 is manipulated so as to establish an hydrauliccircuit which extends from the sump S, through the pump P2, the conduitsection 21, a conduit system 39, the valve V4, a conduit section 41, thelift cylinder 144, a conduit section 43, the valve V4, a conduit section45, and the conduit section 19 back to the sump 8. Introduction of fluidunder pressure into the cylinder [44 from the conduit section 41 willcause the plunger 142 (see FIGS. 2, 6 and 8) to be extended, thuscausting the traverse carrier frame 54 to rock about the horizontal axisof the trunnions 177 in a counterclockwise direction as viewed in FIGS.2 and 8, and in a clockwise direction as viewed in FIG. 6, therebyraising the discharge end of the boom 52. Reverse rocking of thetraverse carrier frame 54 in order to lower the discharge end of theboom is accomplished by manipulating the valve V4 so as to establish anhydraulic circuit extending from the sump S, through the pump P2, theconduit sections 21, 31, the valve V4, the conduit sections 45, 19 backto the sump S.

It is believed that the above description, when considered in the lightof the disclosure of FIGS. 11 and 12 which have been briefly describedheretofore, will suffice for an understanding of the various operativeconveyor boom positions which may be attained for concrete pouringpurposes. In addition to these infinitely variable operative positions,the conveyor boom 52 is capable of being stored alongside the truckchassis or frame structure 12 in an inoperative or parked" position asshown in dotted lines in FIG. 1.

To bring the conveyor boom 52 to this parked position from any one ofthe operative positions of which it is capable of assuming, the boomwill first be brought to its fully extended position by manipulating thevalve V2 as previously described. Thereafter, with the boom fullyextended, the over-center toggle device 220 (see FIG. is manipulated torelease the dog 214 from the cogwheel sector 180, after which the hingedturntable support bracket 58 is swung in a counterclockwise direction asviewed in FIG. 1 until it assumes a transverse position with respect tothe truck chassis or frame structure I2, such position being illustratedin dotted lines FIG. I. With the bracket 58 in its dotted line positionas shown in FIG. I, the over-center toggle device 206 (see FIG. 10) willbe manipulated to release the dog 204 from the cogwheel 170, after whichthe conveyor boom (which at this time is fully extended as previouslymentioned) will be swung in a counterclockwise direction as viewed inFIG. I in order to bring the same to a longitudinal position alongsidethe truck frame structure 12 and above the rear right fender 256 of thetruck and in wrap-around relationship with respect to the rearright-hand corner of the vehicle chas- SIS.

In order that the conveyor boom 52 may clear the fender 256 when it isbeing moved toward its parked position as previously described, theleveling valve V3 is manipulated to shift the position of the pendulumbracket 60 to a slightly inclined position wherein the distal end of thehinged turntable support bracket 58 (and consequently, the conveyor boom52 as a whole) is elevated above the level of the fender 256. After theboom 52 has been swung towards the truck frame structure 12 and isdisposed above the fender 256. the valve V3 will again be manipulated inorder to level the turntable support bracket 58 and, thus, lower theconveyor boom 52 onto the fender 256. In order to prevent dislodgment ofthe conveyor boom 52 from its parked position on the right rear fender256, one or more marginal retaining flanges 258 are provided on theouter side edge of the fender. Additionally, if desired, the conveyorboom 52 may be strapped in its parked position by the use of a suitablestrapping arrangement (not shown).

At such time as the conveyor boom 52 is thus parked or shifted into itsstored and inoperative position, the hinged support bracket 58 of theconveyor system 50 extends transversely across the rear end of thevehicle frame structure 12 and extends alongside the mounting fixture62. At such time as the boom is lowered onto the fender 256 under thecontrol of the valve V3 and the leveling cylinder 188 as previouslydescribed, the support bracket becomes lowered to its substantiallyhorizontal position so that the upper frame bar 192 of the supportbracket enters the confines of a hook-like bracket 259 (see FIGS. 1 and5) on the mounting fixture 62 and, thus, said support bracket 58 is heldagainst dislodgment while the conveyor beam is in its so-called parked"position.

In FIGS. l4, l5 and 16 of the drawings, a slightly modofied form of theinvention is disclosed. In this latter form of the invention, the dogand cogwheel arrangements 180, 214 and 170,204 (see FIG. 10) which areassociated with the hinged turntable support bracket 58 are replaced bythe substitution of a modifled form of hinged support bracket 358 whichemploys locating pins and index wheels in place of the dog andcogwheels. In view of the similarity between the turntable supportingbracket 358 and the supporting bracket 58, and in order to avoidneedless repetition of description, similar reference numerals but of ahigher order have been applied to the corresponding parts as between thedisclosures of FIGS. I4, 15 and 16 on the one hand and FIGS. 9 and 10 onthe other hand.

The support bracket 358 includes upper and lower frame members 492 and494 and is devoid of diagonal struts. The tubular sleeves 474 and 476remain substantially the same as the sleeves I74 and 176 of the supportbracket 58, but the cogwheel I of the lastmentioned bracket is replacedby an index plate in the form of a circular index wheel 470 while thecog segment 180 of the support bracket 58 is replaced by an arcuateindex segment 480. The index wheel 470 is provided with a circularseries of locating holes 471 which establish the various angularpositions of which the conveyor boom is capable of assuming and theseholes cooperate with a locating pin 473 which projects verticallythrough the upper frame member 492 of the hinged turntable supportbracket 358 and is biased upwardly by means of a helical compressionspring 485. The latter surrounds the pin, bears at its lower end againstthe upper frame member 492, and abuts at its upper end against a collar477 which is carried by the pin 473 in the upper region thereof. Thelower end of the pin 473 is pivotally connected to a cam block 479 ofgenerally rectangular configuration. A manipulating lever 481 which iswelded at its proximate end to the block 479 enables said block to beturned back and forth between the position in which it is shown in FIG.l5 and wherein the pin 473 is retracted from cooperation with the indexwheel 470, and the position wherein it is shown in FIG. 16 in which thepin projects through a selected hole 471 and, thus, locks the turntable456 and the U-stand 460 in a desired angular position. A truncatedcorner 483 of the block 479 facilitates turning of the block through the90 angle which is traversed by the block when moving between its twoextreme positions.

The arcuate index segment 480 cooperates with an articulated locatingpin assembly which is identical to the assembly previously described inconnection with the index wheel 470, the two assemblies being designatedin the drawings by identical reference numerals.

The invention is not to be limited to the exact arrangement of partsshown in the accompanying drawings or described in this specification asvarious changes in the details of construction may be resorted towithout departing from the spirit or scope of the invention. Forexample, while the mounting fixture 62 for the pendulum bracket 60 isdisclosed herein as being positioned on the truck chassis or framestructure 12 in the vicinity of the rear left-hand fender 254 of thetruck, such fixture would serve its intended purpose if it were mountednear the right-hand fender 256. In such an instance, the conveyor boom52 would, in the parked position thereof, overlie the left rear fender254 while the panel 252 for the valves V1, V2, V3, and V4 would bepositioned on the rear portion of the right rear fender 256. Theinvention is, however, not necessarily designed for use as a mountedadjunct on a concrete ready-mix truck. [t is within the purview of theinvention fixedly to mount the present distributing conveyor system 50on a vehicle other than a ready-mix truck, or on a stationary support inthe vicinity of concrete-pouring operations, in which cause the same maybe operated in the same manner as has been described herein. it is alsowithin the purview of the invention for the system to distributeflowable material other than wet concrete. Therefore, only insofar asthe invention is particularly pointed out in the accompanying claims isthe same to be limited.

Having described the invention what I claim as new and desire to secureby Letters Patent is:

I. In combination with a vehicle having a frame structure and designedfor the transport of flowable material, a support bracket having itsproximate end hingedly secured to the rear end of said frame structurefor swinging movement about a substantially vertical axis, a turntablemounted on the distal end of said support bracket for rotation about avertical axis, a carrier frame mounted on said turntable for rotationbodily therewith, an longated conveyor unit of the endless belt typeslidably mounted on said carrier frame for lengthwise sliding movementon the frame in opposite directions between a first extreme positionwherein one end thereof is in close proximity to the carrier frame andthe other end is remote therefrom, and a second extreme position wheresaid other end is in close proximity to the carrier frame and said oneend is in close proximity thereto, and a material-receiving hopper onsaid carrier frame, said conveyor unit. in all positions of which it iscapable of assuming, remaining in effective material-receiving registerwith said hopper, the effective length of said support bracket beinggreater than the distance between the hinge connection between thebracket and frame structure and the lateral side of said vehicle framestructure, whereby the distal end of the support bracket overhangs saidrear end of the vehicle frame structure in a transverse direction whenthe support bracket is swung to a transversely extending position withrespect to the vehicle, the turntable being rotatable throughout anangle of sufficient extent to bring the conveyor unit alongside thevehicle in a longitudinally extending relationship when the conveyorunit is in one of its extreme positions.

2. The combination set forth in claim I and wherein the support bracketis also mounted on the vehicle frame structure for limited turningmovement about a horizontal axis which extends longitudinally of saidframe structure, whereby small increments of turning movement about suchhorizontal axis will effect raising and lowering of the carrier frameand the conveyor unit supported thereby.

3. The combination set forth in claim 2 and wherein said vehicle framestructure is generally rectangular, the support bracket is hingedlyconnected to the vehicle frame structure in the vicinity of one of therear corners of the vehicle frame structure, and the effective length ofthe support bracket is greater than the transverse width of said rearend of the vehicle frame structure.

4. The combination set forth in claim 1 and wherein said turntable hasmounted thereon a U-stand consisting of a base member which extendsdiametrically across the turntable and is provided with upstandingvertical side legs, the carrier frame includes structural side memberswhich are maintained in spaced apart relationship by transverse framemembers, the vertical side legs of the U-stand straddle said structuralside members, and trunnions extend between said side members andvertical side legs and serve pivotally to connect the carrier frame tothe turntable for rocking movement about a horizontal axis.

5. The combination set forth in claim 4 and wherein the trunnions arefixedly secured to the upper portions of the vertical side legs of theU-stand.

6. The combination set forth in claim 1 and wherein the carrier frame ispivotally mounted on said turntable for rocking movement about ahorizontal axis whereby, upon rocking movement thereof, the elevationsof the opposite ends of the conveyor unit will be varied in oppositedirections, the carrier frame includes structural side members which aremaintained in spaced apart relationship by transverse frame members,each side member having mounted thereon an upper series of at least twolongitudinally spaced traction rollers and a lower series of at leasttwo longitudinally spaced traction rollers, and the conveyor unit isprovided with an upwardly facing rail surface which cooperates with andunderlies the upper series of traction rollers on each side member, anda downwardly facing rail surface the conveyor unit is provided onopposite sides thereof with laterally-facing channels having upperflanges which establish said upwardly facing rail surfaces, and lowerflanges which establish said downwardly facing rail surfaces.

l l' l i l

1. In combination with a vehicle having a frame structure and designedfor the transport of flowable material, a support bracket having itsproximate end hingedly secured to the rear end of said frame structurefor swinging movement about a substantially vertical axis, a turntablemounted on the distal end of said support bracket for rotation about avertical axis, a carrier frame mounted on said turntable for rotationbodily therewith, an longated conveyor unit of the endless belt typeslidably mounted on said carrier frame for lengthwise sliding movementon the frame in opposite directions between a first extreme positionwherein one end thereof is in close proximity to the carrier frame andthe other end is remote therefrom, and a second extreme position wheresaid other end is in close proximity to the carrier frame and said oneend is in close proximity thereto, and a material-receiving hopper onsaid carrier frame, said conveyor unit, in all positions of which it iscapable of assuming, remaining in effective material-receiving registerwith said hopper, the effective length of said support bracket beinggreater than the distance between the hinge connection between thebracket and frame structure and the lateral side of said vehicle framestructure, whereby the distal end of the support bracket overhangs saidrear end of the vehicle frame structure in a transverse direction whenthe support bracket is swung to a transversely extending position withrespect to the vehicle, the turntable being rotatable throughout anangle of sufficient extent to bring the conveyor unit alongside thevehicle in a longitudinally extending relationship when the conveyorunit is in one of its extreme positions.
 2. The combination set forth inclaim 1 and wherein the support bracket is also mounted on the vehicleframe structure for limited turning movement about a horizontal axiswhich extends longitudinally of said frame structure, whereby smallincrements of turning movement about such horizontal axis will effectraising and lowering of the carrier frame and the conveyor unitsupported thereby.
 3. The combination set forth in claim 2 and whereinsaid vehicle frame structure is generally rectangular, the supportbracket is hingedly connected to the vehicle frame structure in thevicinity of one of the rear corners of the vehicle frame structure, andthe effective length of the support bracket is greater than thetransverse width of said rear end of the vehicle frame structure.
 4. Thecombination set forth in claim 1 and wherein said turntable has mountedthereon a U-stand consisting of a base member which extendsdiametrically across the turntable and is provided with upstandingvertical side legs, the carrier frame includes structural side memberswhich are maintained in spaced apart relationship by transverse framemembers, the vertical side legs of the U-stand straddle said structuralside members, and trunnions extend between said side members andvertical side legs and serve pivotally to connect the carrier frame tothe turntable for rocking movement about a horizontal axis.
 5. Thecombination set forth in claim 4 and wherein the trunnions are fixedlysecured to the upper portions of the vertical side legs of the U-stand.6. The combination set forth in claim 1 and wherein the carrier frame ispivotally mounted on said turntable for rocking movement about ahorizontal axis whereby, upon rocking movement thereof, the elevationsof the opposite ends of the conveyor unit will be varied in oppositedirections, the carrier frame includes structural side members which aremaintained in spaced apart relationship by transverse frame members,each side member having mounted thereon an upper series of at least twolongitudinally spaced traction rollers and a lower series of at leasttwo longitudinally spaced traction rollers, and the conveyor unit isprovided with an upwardly facing rail surface which cooperates with andunderlies the upper series of traction rollers on each side member, anda downwardly facing rail surface which cooperates with and overlies thelower series of traction rollers on each side member.
 7. The combinationset forth in claim 6 and wherein the rollers of said upper and lowerseries are arranged in vertically aligned pairs.
 8. The combination setforth in claim 7 and wherein the conveyor unit is provided on oppositesides thereof with laterally-facing channels having upper flanges whichestablish said upwardly facing rail surfaces, and lower flanges whichestablish said downwardly facing rail surfaces.